Neutral esters of thiolphosphoric acid



Patented May 20, 1952 UNITED STATES PATENT OFFICE NEUTRAL ESTERS- g!THIOLPHOSPHORIC A D Gerhard Schrader, Opladen-Bruchhausen, Germany,assignor to Farbenfabriken Bayer, Leverkusen, Germany No Drawing.Application September 11, 1950, Serial No. 184,335. In Germany May 7,1949 1 The present invention relates to the manufacture of neutralesters of thiolphosphoric acid,

and to new esters of this series.

Hitherto the neutral esters of thiolphosphoric acid of the formula:

alkyl. 0 0

alkyl. 0 S alkyl in particular the esters in which alkyl of the aboveformula is methyl, ethyl, propyl and isobutyl, were prepared by reactingsalts of thiolphosphoric acid of the formula:

alkyl. 0 O

alk.0\ %O alkali NCS.alkyl alk.0\ O

The reaction is most conveniently carried out in an inert solvent, e. g.in benzene or its homologues, chlorobenzene and also in ketones such asacetone, methyl ethyl ketone, methyl propyl ketone, and others. Slightheating, as a rule to about 40 to 60 0., is required. The alkyl radicalsof the alkyl thiocyanates employed may belong to the lower or higheralkyls such as methyl, ethyl, propyl, butyl, hexyl, dodecyl. Also alkylthiocyanates containing the SON- group twice may be used in which casethe reaction shown in the above equation will take place with twomolecules of the alkali salts of dialkyl phosphites. Besides alkylthiocyanates, also aralkyl thiocyanates may be used.

These neutral aliphatic esters of thiolphosphoric acid are, as a rule,oily liquids of a high i 4 Claims. (Cl. 260-461) 2 boiling point, andare distinguished by insecticidal properties.

It has further been found that neutral esters of thiolphosphoric acid ofparticular value and interest are obtained when in the above describednew process instead of simple alkyl thiocyanates thiocyanates of theformula R. S. alk. SCN are used. R in this formula means alkyl,preferably methyl or ethyl, or aryl, in particular phenyl or substitutedphenyl. The radical designated alk in this formula stands for a straightor branched alkylene chain. Compounds obtained by means of thesethiocyanates correspond to the general formula:

in which R1 and R2 are alkyl radicals which may be the same ordifferent, and are preferably lower radicals such as methyl, ethyl, orpropyl. These new esters of thiolphosphoric acid are distinguished byvery good insecticidal properties, in particular by their systemicinsecticidal properties.

It has further been found that these valuable compounds can also beprepared by reacting alkali dialkyl thiophosphates with mercapto alkylhalides of the formula R. S. alk. hal. The alkali dialkyl thiophosphatesreact, as is known, e. g. from Journal of American Chemical Society 6'7[1945], pp. 1662-1664 (T. W. Mastin, G. R. Norman and E. A.Weilmuenster) in their tautomeric form 2:

O.alkali Rlo 1 2 The reaction takes place according to the followingequation:

R 0 Salkali R O\ O R 0 B.a1kali hel.alk.S.R

R 0 S.alk.S.R alkali halide It is carried out in the presence of inertsolvents of the kind mentioned above at elevated temperatures, usuallyat about 40 to about 0.

Another new process of preparing these com pounds consists in reactingdialkyl phosphoric chlorides with alkali salts of mercapto alkyl mer- 3captans of the formula R. S. alk. SH. The reaction takes place accordingto the following equation:

Also here the reaction is carried through in the presence of an inertsolvent ofxthe mentioned kind at elevated temperatures, usually at about40 to about 100 C.

Neutral aliphatic esters of. thiophosphoricaeid substituted in one estergroup by the. radical of an aliphatic or aromatic mercaptan obtainableby one of the forementioned processes are e. g.:

0,0-diethyl s-fi-ethylmercapto' ethyl thiolphosphate 0,0-diethylS-B-methylmercapto=ethyl thiollzphosphate 0,Q-.diethy1 S-3A-methylphenylmercaptoeethyl thiolphosphate O,O -die.thylS-ethylmercapto-methylthiolphos- *phate 0,0-ediethylzSHiemethylphenyImercaptoemethyl :thiolphosphate 0,0-di-1isopropyl s-pethylmercapto-ethyli;tliio1- lxphosphate The present invention isillustrated btfithefollowing examples; it is, however, not restrictedthereto:

Example 1 70 grams of diethyl phosphite are mixedwith 2 cc; of absolutealcoholand diluted with 100 cc. of toluene: 12 grams of sodium arecaused to act uporr the solution thus "obtained: When the sodium hasdissolved, 37 grams of methyl thiocyanate are added dropby drop withstirring at 40 Cb Stirring is-continued at40 C. for 2 hours.

15 cc. of water are then added to the reaction mixture and r theprecipitated salts are removed by filtering." 48 grams of 0,0-dimethylS-nethyl thiolphosphatehaving -a-boiling pointof 112-113" C: at 14==mm.'pressure are obtained. The *prod not is soluble in-Water.

Example 2 "Sodium salt prepared from 12' grams of sodium and 70 grams ofdiethyl phosphite in benzene as described in Example 1 is heated to45-50" C. with stirring. At'this temperature'l grams of ethylthiocyanate are added drop, by drop Within 10 minutes" controlling thetemperature by cooling. The reaction mixture is then heated to 55 C.ior-::one;hour.c.After-workingup as usual grams of 0,0-diethyl S-ethylthiolpho'sphate, boiling at 98 C. at 2 mm. pressure, are obtained. Thenew product is soluble in water to a limited degree.

Example 3 52 grams of n-propyl thiocyanate are reacted at 40 C. with thesodium salt prepared from 12 grams of sodium-and '70 grams of diethylphosphiteinzbenzene as described in Example 1. Thereactionmixturesobtained is heated to 55 C. for one hour andthen workedup' as usual. 40 grams of OD-diethyl S1-propyl thiolphosphate, boilingat.103-1053.C. at .1- mm. pressure, are obtained. Theproduct isinsolublein. water.

phite as described in Example 1.

4 Example 4 57.5 grams of isobutyl thiocyanate are reacted at 40 C. withthe sodium salt prepared from 12 grams of sodium and 70 grams of diethylphosphite as described in Example 1. The reaction mixture. thus obtainedis heated to 55 C. for one hour and subsequently worked up as usual. 74grams of 0,0'-diethy1 S-isobutyl thiolphosphate, boiling at 105 C. at .5mm. pressure, are obtainedJi'iThe product is insoluble in water.

Ezcample 5 65 gramsof n-hexy'l thiocyanate are reacted at 40? C..withthesodium salt prepared from 12 grams of sodium and 70 grams of diethylphos- The reaction mixture is heated to' 55-60 C. for one hour andWorked up as usual. 48 grams of 0,0-diethyl S-hexyl thiolphosphate ofthe boiling point C. at .1 mm. pressure are obtained.

- Example 6 115 grams of dodeoyl thiocyanate are reacted at-50 C; withthe-sodium salt preparedfrom 12 grams of sodium and '70 grams of diethylphosphite as described in'Example 1. The reaction mixture is heated to5560 C. for one hour and is then worked up as usual. 60 grams of0,0-diethyl S-dodecyl thiolphosphate, having a boiling point of 185-190"C. at. .5: mm. pressure; are obtained.

Emample 7 The sodium salt prepared from 12 grams of 'sodium and '70grams of diethyl phosphite as described in Example 1 is heated to 45 C.At this temperature 76 grams ofbenzyl thiocyanate are added drop by dropwith stirring. The reaction mixture' is-further heated to 40 C. forhalfan hour and is then-workedup asusual. 70'grams of 0,0-diethylS-benzyl thiolphosphate with a boiling point of 165-17 0 C. at 2'mm.'pres sure are obtained.

Example 8 Example 9 [grams of sodium are suspendedin' ,cc. of toluene. I42. grams of diethyl phosphite are added and the mixture isstirred at'4050 C., until'allsodium is. dissolved. With stirring 44 grams of ,9ethylmercapto ethyl thiocyanate (boiling at 90 C. at 1mm. pressure) areadded drop bydrop at a temperature of 40 C. The.

mixture is kept for one .hour at' 50 C. and is then worked up. in theusual manner. .Thus 28 gramsof '(C2H5O)2PO.S.C2H4.S.CzI-I5 boiling at137-141 C.'at 1.mm. pressure are obtained.

The product is alight-yellow oil which is insoluble in water.

Example 1 0 '40 grams of B-methylmercapto-ethyl thiocyanate are addeddrop by drop with stirring art-40 C. to the sodium salt solutionobtained according to Example 9. The temperature is kept for one hour at50 C. and is then worked up in the usual manner. Thus 34 grams ofboiling at l34138 C. at 2 mm. pressure ar obtained. 1

Example 11 63 grams of fl-mercapto-ethyl ethyl sulfide CzH5.S.C2H4.SI-I(described in Annalen der Chemie 240, p. 311) are added to 12 grams offinely dispersed sodium in 1'70 cc. of toluene drop'by drop, whilestirring. The temperature is raised to 60 C. and then kept for half anhour. The sodium will then be dissolved. Thereafter the finely dispersedsodium salt of the mercaptan is cooled to C. Thereto under constantoutside cooling 8? grams of diethyl phosphoric monochloride, dissolvedin 100 cc. of toluene, are added drop by drop within 20 minutes, whilestirring. After adding the chloride the reaction product is kept at roomtemperature for a further hour. By adding 20 cc. of water the salts arethen turned into a filterable form. After distilling oil the toluene theremaining oil distils at a boiling point of 136 C. under 1 mm. pressure.93 grams of 0,0-diethyl S-p-ethylmercapto-ethyl thiolphosphate, aslightly yellow oil, insoluble in water are obtained. Yield: 72 per centof theory.

In a similar way can be obtained:

CgHsO O PS.CH,.OH.S.CH:

boiling at 135 C. under 2 mm. pressure not distillable Example 12 '7grams of finely pulverized sodium are suspended in 100 cc. of toluene.43 grams of diethyl phosphite are added thereto at a temperature of 40C. The temperature of 40 C. is kept for half an hour. Then the sodiumwill be dissolved. Thereafter, 10 grams of sulfur are added to thereaction product at a temperature of 60 and it is then heated foranother hour to 105 C. The sodium diethyl thiophosphate being now finelydispersed is reacted with 34 grams of chloromethyl ethyl sulfideC2H5.S.CH2.C1 (cf. Berichte der Deutschen Chemischen Gesellschaft 69[1936], p. 1612) at a temperature of 55 C. The temperature of thereaction mixture is kept for another hour at 55 C., then 8 cc. of waterare added, the toluene layer is removed and fractionated. 40 grams of0,0-diethyl S-ethyllrnercapto-methyl thiolphosphate of a boiling pointof 129-130" C. at 1.5 mm. pressure are obtained. The yield correspondsto 60 per cent of theory. The new thiolester is insoluble in water.

Example 13 Sodium diethyl thiophosphate finely dispersed is preparedfrom the same quantities as in Example 1. 52 grams of chloromethyl4-methylphenyl sulfide CH3.C6H4.S.CH2.C1 (cf. Berichte der DeutschenChemischen Gesellschaft 69 [1936], p. 16 12) are added to thissuspension. The reaction mixture is heated for 4 hours to 105 C.; theformed salts are then brought into a filterable form by adding 10 cc. ofwater, the toluene layer is separated and fractionated. 60 grams of 0,0diethyl S-4-methylphenylmercapto-methyl thiolphosphate with a boilingpoint of 178 C. under .5 mm. pressure are obtained, corresponding to ayield of 65 per cent. The new substance is a colorless oil insoluble inwater.

Example, 1 4

Sodium diethyl thiophosphate is prepared from the same quantities as inExample 1. To this salt 37 grams of B- chloroethyl ethyl sulfideC2H5.S.C2H4.Cl (cf. Annalen der Chemie 240 [1887], p. 310) are addedat'a temperature of 70 C., while stirring; The reaction mixture is thenheated for another two hours to C., and the salts are removed by meansof water as in the preceding examples. By fractionating the toluenelayer 54 grams of 0,0-diethy1 S-flethylmercapto-ethyl thiolphosphate areobtained, corresponding to a yield of 70 per cent; colorless oilinsoluble in water having a boiling point of 136 C. under 1 mm.pressure.

In a similar way e. g. the following compound can be produced:

C H O boiling at 134 0. under 2 mm. pressure Example 15 7 grams ofsodium :powder are suspended in 100 cc. of toluene and heated with 42grams of diisopropyl phosphite to 50 C., until the sodium is dissolved.Thereafter 9 grams of sulfur are added and the mixture is heated foranother hour to 90-95 C. It is then cooled to 50 C., and at thistemperature 37 grams of p-chloroethyl ethyl sulfide are added drop bydrop. The reaction mixture is kept for further 4 hours at 90-95 C.,while stirring. By adding 5 cc. of water the salts formed are thereuponbrought into a filterable form. After sucking oil the salts the solventis removed from the toluene solution. The remaining crude product is nowkept for 10 minutes at an inside temperature of C. under a vacuum of 2mm. to remove the last traces of the volatile solvent. 0,0-di-isopropylS-B-ethylmercaptoethyl thiolphosphate thus obtained is a brownyellow oilinsoluble in water (60 grams). At a pressure of 2 mm. the ester can onlybe distilled with strong decomposition.

Example 16 Young peach trees infested with peach-aphides are sprayedwith an aqueous solution containing 0.005 per cent of the followingcompound:

P-S. CH CH,.S.CH;

After some hours all aphides are killed.

This aqueous solution may also be used in the presence of alkalinereacting agents for simultaneously combating fungi.

Example 17 Tale is ground with the following substance:

PS.CH2.0H1.S.C2H5

so-that a 5wpen=centidust iszobtained: :Thiss'dust is applied to."branches with -caterpi1lars(Malacosomw-neustria) r'l'hefcaterpillarsware killed after a short-time.

This ,:applicationis a-seontinuationein-part or" myoopending:,.ear1ier;application:Serial' N0'.--94,- 721-; filed May 21,11949.

I claim:

1. As new compounds neutral esters of thiolphosphoric acid ofthegeneral'formula:

whereinaeRi and R2 stand: for lower Lalkyl radi cals, e alk' stands fora lower: alky'leneichain', and R stands for one of the groupconsistingof lower alkyl radicals, phenyl radicals and lower alkylsubstituted" phenyl radicals.

2.- As-new compounds neutral: esters of 'thiol phosphoric acid ofthe-general formula:

Rio

6- wherein R, ..-Rr:- and Rzstandior. lower alkyl radicals, and X is oneof the integers 1 and 2. 3% As new-compound the-neutral ester ofthiolphosphoric acid of the formula:

C|H|O O 0,330 SR'JHiLCHjISDaHt 4;. Aszneweompoundthe neutral esteroilthiolphosphorioacid' of. the formula:

SQC Hi CIhS. CHI

GERHARD SCHRADER.

- No references cited.

1. AS NEW COMPOUNDS NEUTRAL ESTERS OF THIOLPHOSPHORIC ACID OF THEGENERAL FORMULA: